Advanced mobile power systems such as lithium based rechargeable battery packs often include a capacity display of some sort. This capacity display is generally referred to as a State of Charge indicator and may be as complex as a numerical representation of the capacity of the battery, or as simple as a single indicator light for low battery conditions.
The conventional method for recharging these battery pack systems is to provide a plug-in charge connection through a direct household electrical connection, through a vehicle power system, or through a computer power system such as a USB (Universal Serial Bus) port.
Different rechargeable battery technologies require different charging techniques. A popular battery charging technology is called CCCV or Constant Current Constant Voltage charging. This charging technique uses a controlled current to recharge the battery during the first phase of charging. As the battery nears fully charged the charger voltage reaches a point where it is limited and the current is allowed to fall. This method of charging is most commonly used in ion-exchange systems such as Lithium Ion based batteries.
The state of charge system sometimes indicates if the system is charging by flashing either the entire display or by flashing the highest capacity indicator element. This flashing is strictly binary in that it indicates either that the battery is charging or is not charging.
The state of charge indication devices commonly in use do not provide an indication that the system they are monitoring is supplying a load.
Solar, hand-crank and fuel-based charging systems may be used to recharge a portable power system. These chargers have the advantage of providing a portable recharging solution to accompany the portable power storage system. The principle disadvantage of these chargers is that it is difficult or impossible in most applications to determine if the charger is putting out a significant amount of power, or if it is in an optimal configuration to provide power.
Further, there is not a good way to determine if these portable charging solutions are actually producing enough power to exceed the demand of the load which may still be connected to the system.
There exists a need for a graphic state of charge indicator for battery charging systems that provides state of charge indication but also provides more information with respect to recharge rate and discharge rate such that the battery charger can be optimally configured to provide the fastest recharge time possible. There is also a need for such indicator to be easy to read, to be similar in appearance to existing state of charge indicators and to be physically small to fit the natures of these complete portable solutions.